... why do manufacturers even bother with supplying you with the 15amp connector if they know it wont hold? I feel like this is just a recipe for disaster. Any possible methods to help keep the cable cool? ....
Many manufacturers, like Arri, won't terminate the power cord when they sell you the light for this reason. For the same reason many TV studios use 20A stage pins instead of the 15A U-ground Edison plugs. The problem arises when rental houses put the Edison plugs on lights so that they can be plugged into wall sockets. As Adrian Sierkowski mentions above the problem is even worse with M18s.
Even if it is on a dedicated 20A circuit the ballast, cable, and/or the wall receptacle may overheat because the draw of an 1800W HMI is just too close to the threshold of a 20A circuit to operate reliably. The Arri 1800W ballast has an Apparent Power of 2250VA (2600 Max according to the ballast manual) which means it will draw up to 19.5 amps at 115V. Operating this close to the threshold, if there is any line loss from a long cable run, or increased resistance from an overheated/under-rated plug end, the draw of the ballast will climb over 20 Amps.
The same is true of operating them on the 20A circuits of portable putt-putt generators. To the problem of line loss and overheating plug ends, you have the added problem that as you add load on portable generators their voltage output drops. It is not uncommon for a generator to drop 10-15 volts under full load. The 1800W ballast that drew 19.5 Amps at 115 Volts will draw 21.4 Amps at 105 Volts.
For these reasons, I am convinced that the 1800W power class was designed primarily for the EU market where its Apparent Power of 2250VA fits comfortably in a 13A/230V circuit. Here they work best on a real film distribution system where every circuit is 20 Amps, you know what is on the circuit because you are loading it yourself, and you are bringing the receptacle to the light because you are distributing the power yourself from a tie in or generator. When you can run a 60A whip and drop a Snack Box next to the light you won’t have a problem. But, if your style of shooting requires that you run multiple stingers to plug into a wall or generator outlet, you will likely have problems with the plug ends or receptacle overheating and causing the breaker to overheat and trip.
I have found that the only reliable way to power a 1800W Baby Max on wall out-lets or on portable gas generators is from a 240V circuit through a 240v-to-120v step-down transformer. A transformer will convert the 240V output into a single large 120V circuit that is more capable of powering the 19.5A load of a 1800W Baby Max. If you outfit the transformer with a 60A Bates receptacle, it enables you to use a real film style distro system that will allow you to move the generator off set (where it won’t be heard), minimize line loss over a long cable run, and provide plug-in pockets close to the ballasts. If you tap the transformer to boost the voltage slightly, it can compensate for the voltage drop on the generator and line loss on the cable, and provide the M18 ballast full line level on set.
A transformer will also enable you to run 1800W Arri Baby Maxs on house power from common 240v household outlets as well. Just like it does with a generator, a transformer will step down the 240V power of common high voltage household outlets to a single 120V circuit capable of powering multiple 1800W Baby Maxs. Common 240V sources found on interior locations include Range Plugs, Dryer Plugs, and special receptacles installed for Window Air Conditioners. By giving you access to more house power through common 240V household outlets, a transformer also enables you to run a real distro system without the need for a dangerous tie-in or expensive tow generator.
For more detailed information on successfully operating the Arri M18 in 120V land, I would suggest you read a white paper I wrote on the use of portable generators in motion picture production.
The white paper is cited in the 4th Edition of Harry Box's “Set Lighting Technician's Handbook" and featured on the companion website. Of the article Harry Box exclaims:
“Great work!... this is the kind of thing I think very few technician's ever get to see, and as a result many people have absolutely no idea why things stop working."
Following the prescriptions contained in this article enables the operation of bigger lights, or more smaller lights, on portable generators than has ever been possible before."
The article is available online at http://www.screenlig...generators.html.
Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rentals & Sales in Boston